The vent holes seemed to fix the problem. It was kind of a unique situation because the geometry wasn’t flagged by PreForm and it was also kind of misleading visually.
It was basically a cylindrical shape with a post in the middle that had a hole running through the center. When placed in a vertical orientation in PreForm it didn’t flag cupping but once it was tilted it flagged it correctly.
The hole in the middle was misleading because at first glance it looked like it would act as a vent hole…however because the hole ran through a post in the middle, there are layers that basically have two polymerized rings concentric to each other. The outermost ring cavity created a vacuum because the inner ring would block air from escaping the middle hole.
Anyhow, it’s definitely a bug in PreForm to not have caught that! Adding vent holes fixed the problem entirely. I was getting tanks that would break/leak after one or two prints and was getting absolutely crazy deformation that I had never seen before. If you want to reach out via email to know more, just hit me up!